This invention relates to capillary electrophoresis, and in particular to structures for holding capillary tubes. Aligning the tubes in the light path for directing liquid flows, and securing electrical contacts for electrophoretic separations in such tubes.
Capillary electrophoresis offers advantages over other types of electrophoresis for certain applications. These advantages include the separation of extremely small samples, a long separation path permitting the separation of a multitude of components in a single sample including those which are closely related, and the use of a high voltage to achieve the separation in a relatively short period of time. Capillary tubes further permit on-line detection of the separated species by passing a light beam through the tube at a point towards its exit end, and directing the emerging light beam to a detector.
Difficulties associated with the use of capillary tubes include the awkwardness of handling involved in sample injection, in connecting and disconnecting the tubes to anolyte and catholyte solutions, and in changing the anolyte and/or catholyte solutions for purposes of zone mobilization and other procedures involved in the separations. A further difficulty is in controlling the Joule heating caused by the high voltage and the zone broadening which often occurs as a result. In the case of on-line detection, difficulties arise in achieving and maintaining proper alignment of the tube in the optical path of a detector and avoidance of drift due to the Joule heating.